Looking for missing part

Hello there!

Thanks for reaching out to us. We might be able to help with this. Can you show us a photo of the mortise lock? That should help with our search for the handle. 

Thank you! This looks to be the 82-238. With that in mind, I recommend you have a look at the 82-080 handle set. The 82-081 is the keyed version. Take a look and see if the specifications match what you're searching for.

Dimensions for 82-080

Thumb lever for 82-080